Electrified interfacial oxygen-down water boosts efficient and durable electrolysis

The oxygen evolution reaction proceeds through proton-coupled electron transfers, mastering interfacial proton dynamics is therefore the critical nexus for simultaneously achieving high catalytic activity and long-term stability. Herein, we establish an oxygen-down water adlayer (H2O ↓ ) that concurrently optimizing initial water deprotonation and subsequent proton transport. We engineer edge dislocations into RuO2 to create stress fields that exert differential electrostatic forces on water, anchoring oxygen while repelling protons and thereby enforcing the H2O↓ orientation, which is directly evidenced by a molecular dipole angle (θw) of ~67°at 1669 cm-1 peak in infrared spectroscopy. In situ spectroscopy and simulations confirm that the H2O↓ layer forms a rigid hydrogen-bond network that accelerates Grotthuss-like proton shuttling, preventing corrosive local acid accumulation. The pre-aligned water molecules bypass the stochastic reorientation step, reducing the oxygen formation barrier from 2.02 eV to as low as 0.85 eV. Consequently, our RuO2 catalyst achieves 10 mA cm-2 at 179 mV overpotential with >1,000-hour stability, and enables high current density at 1 A cm-2 for >720 hours at 1.75 V. The oxygen evolution reaction is hindered by slow proton transfer. Here, the authors report an ordered oxygen-down water layer that accelerates initial water deprotonation and proton transport, enabling low-voltage, durable membrane electrolysis at high current.